To study further the natural history of two major components of diabetic retinopathy: (1) Maculopathy of background retinopathy; (2) Proliferative retinopathy emanating from the disc. Standard fluorescein angiography techniques along with scanning densitometry studies of the photographs will be performed. A detailed correlation of ophthalmoscopic and fluorescein findings will be made in reference to the eyes of patients who come to autopsy in a special study. Further investigation of an experimental model of proliferative retinopathy produced by oxygen exposure of young animals will be performed in an attempt to identify factors related to retinal ischemia and retinal vasoproliferation. Further development of a photocoagulation technique to permit safe treatment through mild vitreal hemorrhage of underlying neovascularization in the diabetic patient with a minimal of energy absorption in the vitreal blood.